Liquid crystal device, light emitting device, electronic apparatus, method of controlling liquid crystal device, and method of controlling light emitting device

ABSTRACT

A liquid crystal device is provided. The liquid crystal device includes: a liquid crystal panel including a pair of substrates which interpose a liquid crystal layer; a plurality of light receiving elements which detect ambient light; and a control unit which controls a display state of an image displayed on the liquid crystal panel based on an intensity of the ambient light detected by a plurality of the light receiving elements, wherein the control unit includes a determination unit determining that the intensity of the ambient light is changed when changed amounts of the intensities of the ambient light detected by equal to or more than half of the light receiving elements exceed a predetermined value.

BACKGROUND

1. Technical Field

The present invention relates to a liquid crystal device, a lightemitting device, an electronic apparatus, a method of controlling aliquid crystal device, and a method of controlling a light emittingdevice.

2. Related Art

In general, a liquid crystal device used as a display unit of anelectronic apparatus includes a liquid crystal panel and a backlightwhich is disposed at the rear surface of the liquid panel as anillumination unit.

The backlight of the liquid crystal device may be an LED (Light EmittingDiode). A control circuit that controls an intensity of illuminationlight by adjusting current supplied to the LED is disposed in the liquidcrystal device. In order for the liquid crystal panel to performdisplaying with good quality according to external brightness of theelectronic apparatus, there has been proposed an liquid crystal deviceincluding an optical sensor which detects an intensity of the ambientlight and a control circuit which adjusts an intensity of a backlightbased on the detection result obtained by using the optical sensor (seeJP-A-2005-121997).

However, the liquid crystal device in the related art has the followingproblems. In the liquid crystal device of adjusting the intensity of theillumination light based on the intensity of the ambient light, forexample, when a light receiving surface of an optical sensor is shieldedwith a hand (light shielding member) in mistake, the control circuit maydetermine that the intensity of the ambient light becomes weak.Therefore, there is a problem of malfunction that the intensity of thebacklight may be adjusted based on the erroneously determined intensityof the ambient light.

SUMMARY

An advantage of some aspects of the invention is to provide a liquidcrystal device, a light emitting device, an electronic apparatus, amethod of controlling a liquid crystal device, and a method ofcontrolling a light emitting device capable of preventing malfunctioneven though a light receiving surface of an optical sensor is shieldedwith a light shielding member in mistake.

According to an aspect of the invention, there is provided a liquidcrystal device comprising: a liquid crystal panel including a pair ofsubstrates which interpose a liquid crystal layer; a plurality of lightreceiving elements which detect ambient light; and a control unit whichcontrols a display state of an image displayed on the liquid crystalpanel based on an intensity of the ambient light detected by a pluralityof the light receiving elements, wherein the control unit includes adetermination unit determining that the intensity of the ambient lightis changed when changed amounts of the intensities of the ambient lightdetected by equal to or more than half of the light receiving elementsexceed a predetermined value.

According to another aspect of the invention, there is provided a methodof controlling a liquid crystal device including a liquid crystal panelincluding a pair of substrates which interpose a liquid crystal layerand a plurality of light receiving elements which detect ambient light,the method comprising: detecting an intensity of the ambient light byusing a plurality of the light receiving elements in a predeterminedtime interval; and controlling a display state of an image displayed onthe liquid crystal panel by determining that the intensity of theambient light is changed when changed amounts of the intensities of theambient light detected by equal to or more than half of the lightreceiving elements exceed a predetermined value.

In the aspects of the invention, in a case where a portion of the lightreceiving elements are shielded with a hand in mistake or irradiatedwith light in mistake, even though the intensity of the ambient lightdetected by the light receiving elements is determined to be weak orstrong, if the changed amounts of the intensities of the ambient lightdetected by equal to or more than half of the light receiving elementsdo not exceed a predetermined value, the intensity of the ambient lightis determined not to be changed. Therefore, although the intensitiesdifferent from actual intensities of a portion of the light receivingelements are detected, it is possible to prevent an erroneous conversionof the display state of an image displayed on the liquid crystal panel.

In addition, even though a portion of the light receiving elements arein disorder not to detect the ambient light, other light receivingelements can detect the ambient light, so that the display state of theimage displayed on the liquid crystal panel can be converted.

In addition, in the liquid crystal device according to the aboveaspects, it is preferable that the determination unit determines thatthe intensity of the ambient light is changed when changed amounts ofthe intensities of the ambient light detected by more than half of thelight receiving elements exceed a predetermined value.

In the aspects of the invention, the intensity of the ambient light isdetermined to be changed when the changed amounts of the intensities ofthe ambient light detected by more than half of the light receivingelements exceed a predetermined value, so that it is possible to moreeffectively prevent occurrence of malfunction.

In addition, in the liquid crystal device according to the aboveaspects, it is preferable that the liquid crystal device furthercomprises an illumination unit which irradiates illumination light on arear surface of the liquid crystal panel, and the control unit controlsan intensity of the illumination light based on the determination of thedetermination unit.

In the aspects of the invention, since the control unit controls theintensity of the illumination light irradiated from the illuminationunit based on the intensity of the ambient light, image display can beappropriately performed by the liquid crystal panel irrespective ofbrightness of the ambient light of the liquid crystal device, and powerconsumption for irradiating the illumination light can be reduced.

According to still another aspect of the invention, there is provided alight emitting device comprising: an electro-optical panel including apair of substrates which interpose an electro-optical material layer; aplurality of light receiving elements which detect ambient light; and acontrol unit which controls a display state of an image displayed on theelectro-optical panel based on an intensity of the ambient lightdetected by a plurality of the light receiving elements, wherein thecontrol unit includes a determination unit determining that theintensity of the ambient light is changed when changed amounts of theintensities of the ambient light detected by equal to or more than halfof the light receiving elements exceed a predetermined value.

According to further still another aspect of the invention, there isprovided a method of controlling a light emitting device including anelectro-optical panel including a pair of substrates which interpose anelectro-optical material layer and a plurality of light receivingelements which detect ambient light, the method comprising: detecting anintensity of the ambient light by using a plurality of the lightreceiving elements in a predetermined time interval; and controlling adisplay state of an image displayed on the electro-optical panel bydetermining that the intensity of the ambient light is changed whenchanged amounts of the intensities of the ambient light detected byequal to or more than half of the light receiving elements exceed apredetermined value.

In the aspects of the invention, as described above, although theintensities different from actual intensities of a portion of the lightreceiving elements are detected, it is possible to prevent an erroneousconversion of the display state of an image displayed on theelectro-optical panel.

In addition, the display state of the image displayed on theelectro-optical panel can be optimally controlled based on the intensityinformation, so that it is possible to prevent excessive voltage formbeing applied to, for example, an electro-optical material layer.Therefore, the life cycle of the electro-optical material layer can beprolonged.

According to further still another aspect of the invention, there isprovided an electronic apparatus having the aforementioned liquidcrystal device.

According to further still another aspect of the invention, there isprovided an electronic apparatus having the aforementioned lightemitting device.

In the aspects of the invention, since the aforementioned liquid crystaldevice or light emitting device is provided, although the intensitiesdifferent from actual intensities of a portion of the light receivingelements are detected, it is possible to prevent an erroneous conversionof the display state of an image displayed on the liquid crystal panelor the electro-optical panel.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1A is a plan view showing a liquid crystal device according to anembodiment, and FIG. 1B is a cross-sectional view thereof.

FIG. 2 is a circuit diagram of the liquid crystal device.

FIG. 3 is a view showing a logic circuit provided to a determinationunit.

FIG. 4 is a flowchart showing a determination method performed by adetermination unit according to an embodiment.

FIG. 5 is a perspective view showing an outer appearance of a mobilephone according to an embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, a liquid crystal device and an electronic apparatusaccording to an embodiment of the invention will be described withreference to the accompanying drawings. FIG. 1A is a plan view showing aliquid crystal device according to an embodiment, and FIG. 1B is across-sectional view taken along line IB-IB. FIG. 2 is a circuit diagramshowing a circuit construction of the liquid crystal device.

A liquid crystal device 10 is a semi-transmissive reflective TFT (ThinFilm Transistors) active matrix type liquid crystal device. As shown inFIGS. 1A, 1B, and 2, the liquid crystal device 10 includes liquidcrystal panel 11, a backlight (illumination unit) 12 disposed in therear surface of the liquid crystal panel 11, and a backlight controlcircuit (illumination light control unit) 13 which controls an intensityof the illumination light by adjusting a current supplied to thebacklight 12.

As shown in FIG. 1A, the liquid crystal panel 11 includes a TFT arraysubstrate (a substrate) 22 and an opposite substrate (another substrate)23 which interpose an liquid crystal layer 21 and a sealing member 24which is disposed at edges of facing surfaces of the first and secondsubstrates 22 and 23 and has a substantially rectangular shape as seenfrom a plan view so as to seal the liquid crystal layer 21. In theliquid crystal panel 11, an image display area 25 is defined by an innerportion of a sealed area surrounded by the TFT array substrate 22 andthe opposite substrate 23 which overlap each other and a peripheralshielding layer 51 (described below) which is formed in an inner side ofthe sealing member 24. In the liquid crystal panel 11, the TFT arraysubstrate 22 is a rear side substrate, and the opposite substrate 23 isa front side substrate.

Polarizing plates (not shown) are disposed on the front and rearsurfaces of the liquid crystal panel 11, respectively. A pair of thepolarizing plates transmit only linearly polarized light that vibrate ina specific direction. Transmission axes of the polarizing plates aredisposed to be substantially perpendicular to each other and intersect arubbing direction of the alignment film with an angle of about 45°.

For example, the liquid crystal layer 21 is formed of a liquid crystalin which one type or multiple types of nematic liquid crystals aremixed, and is disposed in a specific alignment state between alignmentfilms (not shown) respectively formed on the TFT array substrate 22 andthe Opposite substrate 23. The liquid crystal layer 21 may have a TN(Twisted Nematic) mode that uses a liquid crystal having a positivedielectric anisotropy or a VAN (Vertical Aligned Nematic) mode that usesa liquid crystal having a negative dielectric anisotropy.

The TFT array substrate 22 has a rectangular shape when seen from a planview and is made of an optical transmissive material such as quartz,glass, plastic, or the like. In addition, the TFT array substrate 22 isformed with a protrusion region 22A which protrudes outwards withrespect to the opposite substrate 23 in one edge thereof.

In a region where the TFT array substrate 22 overlaps the image displayarea 25, a plurality of scan lines 31, signal lines 32, TFTs 33, andpixel electrodes 34 are provided. In side regions of the image displayarea 25 of the TFT array substrate 22, first to third light receivingelements (light receiving means) 35 to 37 are provided. In addition, asignal line driving circuit 38 is disposed along one side of the TFTarray substrate 22. In addition, scan line driving circuits 39 and 40are disposed along two sides adjacent to the one side of the TFT arraysubstrate 22. In the protrusion regions 22A of the TFT array substrate22, there are provided terminals 41, that is, a group of terminals ofthe first to third light receiving elements 35 to 37, the signal linedriving circuit 38, and the scan line driving circuits 39 and 40. Inaddition, the first to third light receiving elements 35 to 37, thesignal line driving circuit 38, the scan line driving circuits 39 and40, and the terminals 41 are suitably electrically connected to eachother with wire lines 42.

As shown in FIG. 2, the scanning lines 31 are wire lines extending inthe X direction and made of a metal such as aluminum. In addition, asshown in FIG. 2, the signal lines 32 are wire lines extending in the Ydirection to intersect the scanning lines 31. Similarly to the scanninglines 31, the signal lines 32 are made of a metal such as aluminum.Pixel areas are formed by the scanning lines 31 and the signal lines 32.

Each pixel area is surrounded by the scanning lines 31 and the signallines 32. In addition, as seen from a plan view, the pixel area isformed to overlap an area where a color filter (not shown) is disposedon the opposite substrate 23.

For example, each of the TFTs 33 is constructed with an n-typetransistor. The TFTs 33 are disposed at intersections between thescanning lines 31 and the signal lines 32. In addition, the TFTs 33 areconstructed by partially forming an amorphous polysilicon layer or apolysilicon layer crystallized with the amorphous polysilicon layer onthe upper surface of the TFT array substrate 22 and partially doping andactivating impurities thereon.

The scanning lines 31 are respectively electrically connected to gatesof the TFTs 33. The pixel electrodes 34 are respectively electricallyconnected to drains of the TFTs 33.

In order to prevent image signals stored in the pixel electrodes 34 fromleaking, storage capacitors 41 are connected to the pixel electrodes 34in parallel.

The pixel electrodes 34 are made of an optical transmissive conductivematerial such as ITO (Indium Tin Oxide). Each of the pixel electrodes 34is arranged to face an opposite electrode 54 (described later) disposedon the opposite substrate 23. In addition, the liquid crystal layer 21is interposed between the pixels electrodes 34 and the oppositeelectrode 54 which is disposed on the opposite substrate 23 to face thepixel electrodes 34. Furthermore, the pixel electrodes 34 are providedwith a reflecting layer (not shown).

The first to third light receiving elements 35 to 37 may be constructedwith a photodiode, a phototransistor, or the like. The first lightreceiving element 35 is disposed so as for a first light receivingsurface 35A, that is, a light receiving surface of the first lightreceiving element 35 to be located at a lower left side of the imagedisplay area 25 in FIG. 1A. The second light receiving element 36 isdisposed so as for a second light receiving surface 36A to be located ata lower right side of the image display area 25, and the third lightreceiving element 37 is disposed so as for a third light receivingsurface 37A to be located at an upper right side of the image displayarea 25. Namely, the first to third light receiving elements 35 to 37are disposed so as for the light receiving surfaces thereof to beseparated from each other at the sides of the image display area 25.Therefore, a probability that more than two of the first to third lightreceiving surfaces 35A to 37A are shielded in mistake can be reduced.

When the backlight control circuit 13 transmits a detection startsignal, the first to third light receiving elements 35 to 37 receive theambient light though the first to third light receiving surfaces 35A to37A and output opto-electrically transformed electrical signals asintensity information to the backlight control circuit 13.

In a case where the first to third light receiving elements 35 to 37 areconstructed with a PIN (Positive Intrinsic Negative) type photodiode,the PIN-type photodiode can be formed such that, when a semiconductorlayer constituting the first to third light receiving elements 35 to 37are defined as an intrinsic semiconductor region (I layer) in which anintrinsic semiconductor or a negligible concentration of impurity isintroduced, a p-type semiconductor region (P layer) is formed in oneside of the intrinsic semiconductor region (I layer), whereas an n-typesemiconductor region (N layer) is formed on the other side thereof. Byutilizing a semiconductor layer that is formed in the same process asthat of the TFT 33, the PIN-type photodiode may be formed in the samemanufacturing process as that of the TFT 33.

As shown in FIG. 2, the signal line driving circuit 38 is constructed soas to supply image signals to a plurality of signal lines 32. Here, theimage signals input to the signal lines 32 by the signal line drivingcircuit 38 may be supplied in the line order or in groups of adjacentsignal lines 32.

The signal line driving circuits 39 and 40 are constructed so as tosupply scan signals to a plurality of scanning lines 31 at apredetermined timing in the form of pulse in the line order.

The signal line driving circuit 38 and the scanning line drivingcircuits 39 and 40 are constructed with an electrical circuit in which atransistor, a diode, a capacitor, and so on are combined, and are formedby partially introducing or activating impurities with respect to anamorphous polysilicon layer or a polysilicon layer crystallized with theamorphous polysilicon layer which is partially formed on the uppersurface of the TFT array substrate 22, like the TFTs 33 or the lightreceiving element 35. Therefore, the signal line driving circuit 38 canbe formed by the same manufacturing process as those of the TFT 33 orthe light receiving element 35.

The terminals 41 are connected to one end of a flexible board 44 byusing an anisotropic conductive material such as an ACF (AnisotropicConductive Film) or an ACP (Anisotropic Conductive Paste). Through theflexible board 44, a timing generating circuit 45 and the scanning linedriving circuits 39 and 40 are electrically connected, a power circuit46, the signal line driving circuit 38, and the scanning line drivingcircuits 39 and 40 are electrically connected, and the first to thirdlight receiving elements 35 to 37 and the backlight control circuit 15are electrically connected. The timing generating circuit 45 isconnected to an image processing circuit 47.

Similar to the TFT array substrate 22, the opposite substrate 23 has arectangular shape as seen from a plan view and is made of an opticaltransmissive material such as glass or plastic. On the lower surface ofthe liquid crystal layer 21 of the opposite substrate 23, the peripheralshielding layer 51, a display area shielding layer 52, a color filterlayer 53, the opposite electrode 54, and an alignment film (not shown)are stacked in this order.

The peripheral shielding layer 51 has a shape of a rectangular frame asseen from a plan view and is disposed along the inner circumferentialsurface of the sealing member 24, to define the image display area.

The display area shielding layer 52 has a grid or stripe shape as seenfrom a plan view and is disposed to cover the image display area 25,that is, an area inside the peripheral shielding layer 51.

The color filter layer 53 is constructed with a plurality of colorfilters which are arranged in matrix as seen from a plan view, so as tocorrespond to the pixel areas described above.

Similar to the pixel electrode 34, the opposite electrode 54 is a flatlayer made of an optical transmissive conductive material such as ITO.

Four corner portions of the opposite substrate 23 are provided withupper and lower conductive materials 55 which function as upper andlower conductive terminals between the opposite substrate 23 and the TFTarray substrate 22. The upper and lower conductive materials 55 are usedto electrically connect the opposite substrate 23 and the TFT arraysubstrate 22.

The sealing member 24 has a shape of a rectangular frame as seen from aplan view and is in contact with the TFT array substrate 22 and theopposite substrate 23. The sealing member 24 is constructed with a UVcurable resin, a thermosetting resin, or the like and is subject to acuring process by irradiating an ultraviolet ray or heating after beingcoated at a specific position of the TFT array substrate 22. Inaddition, the sealing member 24 is mixed with a gap material such asglass fiber or glass beads in order to allow a distance (gap betweensubstrates) between the TFT array substrate 22 and the oppositesubstrate 23 to have a predetermined value.

The backlight 12 includes a light source which is constructed with awhite LED or the like, a light guide plate which guides illuminationlight irradiated by the light source, and a reflector.

As shown in FIG. 2, the backlight control circuit 13 includes adetermination unit (determination means) 58 which is electricallyconnected to the first to third light receiving elements 35 to 37through a flexible board 44 and a current supply unit 59 which iselectrically connected to the backlight 12.

The determination unit 58 transmits the detection start signal to thefirst to third light receiving elements 35 to 37 in a predetermined timeinterval so as to receive the ambient light. The determination unit 58receives the intensity information from the first to third lightreceiving elements 35 to 37 and calculates the intensity of the ambientlight from the received intensity information. In addition, thedetermination unit 58 include a recording unit (not shown) such as amemory which stores the intensities of the ambient light that arepreviously received from the first to third light receiving elements 35to 37 in response to transmission of the detection start signal. Thedetermination unit 58 is constructed to calculate changed amounts of theintensities of the ambient light received by the first to third lightreceiving elements 35 to 37. In addition, as shown in FIG. 3, thedetermination unit 58 includes a logic circuit so as to determine thatthe intensity of the ambient light is changed when the changed amountsof the intensities of more than two of the first to third lightreceiving elements 35 to 37, that is, more than half thereof exceed apredetermined value. A truth table of the logic circuit is as follows.In table 1, if the changed amount of the intensity of each of the firstto third light receiving elements 35 to 37 exceeds a predeterminedvalue, IN1 to IN3 are represented by 1, and if not, by 0. In addition, acase where the determination unit 58 determines that the intensity ofthe ambient light is changed is represented by 1, and a case where thedetermination unit 58 does not determine that the intensity of theambient light is changed is represented by 0. TABLE 1 IN1 IN2 IN3 IN4 11 1 1 1 1 0 1 1 0 1 1 1 0 0 0 0 1 1 1 0 1 0 0 0 0 1 0 0 0 0 00: changed amount exceeds a predetermined value1: changed amount dose not exceed a predetermined value

When the intensity of the ambient light is determined to be changed, thedetermination unit 58 calculates an average value of the intensities ofthe ambient light corresponding to the light receiving elements thatdetect the changed amounts of the intensities of the ambient light amongthe first to third light receiving elements 35 to 37 and outputs theaverage value to the current supply unit 59.

The current supply unit 59 adjusts the current to be supplied to thebacklight 12 based on the intensity of the ambient light calculated bythe determination unit 58 to control the intensity of the illuminationlight.

When the intensity of the ambient light is equal to or less than athreshold value T1, the current supply unit 59 allows the backlight 12to irradiate the illumination light, so that the liquid crystal panel 11is in the transmissive display mode. When the intensity of the ambientlight exceeds a threshold value T2 higher than the threshold value T1,the current supply unit 59 allows the backlight 12 not to irradiate theillumination light, but the ambient light is reflected by the reflectinglayer so as to be used as the illumination light, so that the liquidcrystal panel 11 is in the transmissive display mode.

The liquid crystal device 10 having the aforementioned structure isemployed by a mobile phone (n electronic apparatus) 60 as shown in FIG.4. FIG. 4 is a perspective view of a mobile phone.

The mobile phone 60 includes a body 61 and a cover 62 which is connectedto the lower end of the body 61 via a hinge mechanism. The cover 62 canbe freely open and closed against the body 61. In addition, the body 61includes a display unit 63 constructed with the aforementioned liquidcrystal device 10, an operation unit 64 arranged with a plurality ofoperation keys, an earpiece 65, and an antenna 66. The cover 62 includesa mouthpiece 67.

Now, a method of controlling the intensity of the illumination light ofthe backlight 12 based on the intensity of the ambient light in themobile phone 60 employing the liquid crystal device 10 having theaforementioned structure will be described with reference to FIG. 5.

Firstly, the determination unit 58 transmits a detection start signal tothe first to third light receiving elements 35 to 37, and the first tothird light receiving elements 35 to 37 receives the ambient light (StepST1 in FIG. 5). Next, the first to third light receiving elements 35 to37 outputs opto-electrically transformed electrical signals as intensityinformation to the determination unit 58.

Next, the determination unit 58 calculates changed amounts of theintensities detected by the first to third light receiving elements 35to 37 with respect to the intensity of the ambient light based on thereceived intensity information and stores the changed amounts in therecording unit (Step ST2 in FIG. 5).

The determination unit 58 determines whether or not the changed amountsof the intensities of the ambient light detected by more than two of thefirst to third light receiving elements 35 to 37, that is, more thanhalf thereof, exceed a predetermined value (Step ST3 in FIG. 5). In thedetermination, the intensity of the ambient light detected by the firstto third light receiving elements 35 to 37 at the time of transmissionof the previous detection start signal is read out from the recordingunit and compared with the intensities of the ambient light detected inStep ST1.

If the determination unit 58 determines that the intensity of theambient light is changed in Step ST3, the current supply unit 59 adjuststhe current amount to be supplied to the backlight 12 to control theintensity of the illumination light in the backlight 12 (Step ST4 inFIG. 5). More specifically, the current supply unit 59 controls theintensity of the illumination light in the backlight 12 based on anaverage value of the intensities of the ambient light corresponding tothe light receiving elements that detect the changed amounts of theintensities of the ambient light among the first to third lightreceiving elements 35 to 37.

If the determination unit 58 does not determine that the intensity ofthe ambient light is changed in Step ST3, the intensity of theillumination light in the backlight 12 is maintained (Step ST5 in FIG.5). By doing so, in a case where a portion of the first to third lightreceiving elements 35 to 37 are shielded with a hand (light shieldingmeans) in mistake or irradiated with light in mistake, even though theintensities of the ambient light detected by a portion of the lightreceiving elements are different from an actual intensity of the ambientlight, it is possible to prevent an erroneous adjustment of theintensity of the illumination light. In addition, since the first tothird light receiving elements 35 to 37 are disposed so as for the lightreceiving surfaces thereof to be separated from each other at the sidesof the image display area 25, a probability that more than two of thefirst to third light receiving surfaces 35A to 37A are shielded inmistake can be reduced.

After the intensity of the illumination light is adjusted in Step ST4 orafter the intensity of the illumination light is maintained in Step ST5,it is determined whether or not the image display is continuouslyperformed by the light crystal device 10 (Step ST6 in FIG. 5).

In a case where the image display of the light crystal device 10 iscontinuously performed in Step ST6, after a predetermined time, theoperation returns to Step ST1, and the determination unit 58 transmitsthe detection start signal, so that the detection of the ambient lightis performed again.

In a case where the image display of the light crystal device 10 isfinished in Step ST6, the irradiation of the illumination light ends.

According to the above descried steps, the intensity of the illuminationlight of the backlight 12 is controlled.

According to the liquid crystal device 10 and the methods of controllingthe mobile phone 1 and the liquid crystal devices having theaforementioned construction, in a case where a portion of the first tothird light receiving elements 35 to 37 are shielded with a hand or thelike in mistake or irradiated with light in mistake, even though theintensities of the ambient light detected by a portion of the lightreceiving elements are different from an actual intensity of the ambientlight, if the changed amounts of the intensities of equal to or morethan two of the first to third light receiving elements 35 to 37 do notexceed a predetermined value, the determination unit 58 does notdetermine that the intensity of the ambient light is changed. Therefore,it is possible to prevent an erroneous adjustment of the intensity ofthe illumination light. In addition, in a case where one of the first tothird light receiving elements 35 to 37 is in disorder, the ambientlight can be detected by the other two light receiving elements, so thatthe adjustment of the intensity of the illumination light can beperformed.

In addition, since the intensity of the illumination light is controlledbased on the intensity of the ambient light, image display can beappropriately performed by the liquid crystal panel 11 irrespective ofbrightness of the ambient light of the liquid crystal device, and powerconsumption for irradiating the illumination light can be reduced.

The invention is not limited to the above embodiments, and variouschanges in form may be made therein without departing from the scope andspirit of the invention.

For example, in the aforementioned embodiments, the light receivingelements are disposed at three positions. However, the light receivingelements may be disposed at a plurality of position, for example, twopositions, four positions, or more.

In a case where two light receiving elements are disposed, the two lightreceiving elements may be disposed so as for the light receivingsurfaces thereof at the upper right side and the left side of the imagedisplay area shown in FIG. 1A, respectively. If the intensities of theambient light detected by the two light receiving elements exceed apredetermined value, the determination unit determines that theintensity of the ambient light is changed. If not, the determinationunit does not determine that the intensity of the ambient light ischanged. In a case where four light receiving elements are disposed, thefour light receiving elements may be disposed so as for the lightreceiving surfaces thereof at the lower right, upper right, lower left,and upper left sides of the image display area shown in FIG. 1A,respectively. If the intensities of the ambient light detected by equalto or more than three light receiving elements exceed a predeterminedvalue, the intensity of the ambient light is determined to be changed.If not, the intensity of the ambient light is not determined to bechanged.

In addition, in the aforementioned embodiment, the determination unitdetermines that the intensity of the ambient light is changed when thechanged amounts of the intensities of more than half of the lightreceiving elements exceed a predetermined value. However, thedetermination unit may determine that the intensity of the ambient lightis changed when the changed amounts of the intensities of equal to ormore than half of the light receiving elements exceed a predeterminedvalue. In other word, the determination unit may determine that theintensity of the ambient light is changed even though the number of thelight receiving elements that detect the intensities exceeding apredetermined value is equal to the number of the light receivingelements that detect the intensities not exceeding a predeterminedvalue.

In addition, if the intensities detected by some of the light receivingelements increase to exceed a predetermined value, and if theintensities detected by other of the light receiving elements decreasesto exceed a predetermined value, the outputs of the light receivingelements may be different from each other. In this case, the intensityof the ambient light may be determined not to be changed.

In addition, in the aforementioned embodiment, the current supply unitadjusts the current amount to be supplied to the backlight based on anaverage value of the intensities corresponding to the light receivingelements that detect the intensities of the ambient light exceeding apredetermined value. However, the current amount may be adjusted byusing other methods such as a method of adjusting the current amountbased on the intensity of the ambient light corresponding to one of thelight receiving elements that detect the intensities of the ambientlight exceeding a predetermined value.

In addition, in the aforementioned embodiment, the intensity of theillumination light is controlled based on the intensity of the ambientlight received by the light receiving element. However, an image to bedisplayed on the liquid panel may be corrected based on the intensity ofthe ambient light.

In addition, in the aforementioned embodiment, a semi-transmissivereflective liquid crystal device is used. However, a transmissive liquidcrystal device may be used.

In addition, in the aforementioned embodiment, the light receivingelements are disposed on the TFT array substrate. However, if the lightreceiving surfaces can receive light, the light receiving elements maybe disposed on the opposite substrate. In addition, the light receivingsurfaces may be disposed in the vicinity of a display portion of a caseof a mobile phone.

In addition, in the aforementioned embodiment, a transmissive liquidcrystal device which displays an image on the liquid crystal panel byusing the illumination light irradiated from the backlight irrespectiveof the ambient light is employed. However, a semi-transmissivereflective liquid crystal device which displays an image by using theillumination light of the backlight in case of weak ambient light and byreflecting the ambient light incident on the front surface side of theliquid crystal panel with a reflecting layer in case of strong ambientlight may be employed.

In addition, in the aforementioned embodiment, the liquid crystal panelhas an active matrix structure. However, the liquid crystal panel mayhave a passive matrix structure. In this case, a reed-shaped transparentelectrode is arranged in a stripe form on one side of a substratecorresponding to the TFT array substrate as seen from a plan view, so asto have a structure in which a reed-shaped transparent electrode isarranged in a stripe form on the other side of a substrate correspondingto the opposite substrate, as seen from a plan view, in a cross mannerwith respect to the transparent electrode formed on the one side of thesubstrate.

In addition, in the aforementioned embodiment, the color filter isformed on the upper surface of the liquid crystal layer of the oppositesubstrate. However, the color filter may be formed on the TFT arraysubstrate.

In addition, in the aforementioned embodiment, the liquid crystal deviceis described. However, an electro-optical device such as an organic ELdevice having an electro-optical panel including a pair of substratesmade of a transmissive material which interpose an electro-opticalmaterial layer made of an organic light emitting material that emitslight according to an applied voltage may be employed. In a case wherethe electro-optical device is employed by the present invention, asdescribed above, although the intensities different from actualintensities of a portion of the light receiving elements are detected,it is possible to prevent an erroneous conversion of the display stateof an image displayed on the electro-optical panel. In addition, thevoltage applied to the electro-optical panel is optimized, and anexcessive voltage is not applied to the electro-optical material layer.Therefore, it is possible to prolong life cycle of the electro-opticalmaterial layer. Here, the electro-optical device is not limited to theorganic EL device, but any other electro-optical devices includingelectro-optical penal may be used.

In addition, in the aforementioned embodiment, an electronic apparatusincluding the liquid crystal device is described. However, an electronicapparatus including an electro-optical device may be employed.

In addition, although the peripheral shielding layer is formed on theopposite substrate, the peripheral shielding layer may be partially orentirely placed on the TFT array substrate as an embedded shieldinglayer.

In addition, although the timing generator, the power source circuit,the backlight control circuit are connected to the signal line drivingcircuit, the scanning line driving circuit, the light receiving element,and so on via the flexible board, some or all of them may be formed onthe TFT array substrate, similarly to the signal line driving circuit orthe scanning line driving circuit.

On the surface of the TFT array substrate, in addition to the abovesignal line driving circuit, the scanning line driving circuit, and soon, a sampling circuit that samples and supplies an image signal to asignal line, a pre-charge circuit that supplies a pre-charge signal of aspecific voltage to a plurality of signal lines, respectively, prior tothe image signal, and a test circuit that tests a mobile phone in termsof quality or defect thereof in a manufacturing or shipment process.

Although the signal line driving circuit or the scanning line drivingcircuit is formed on the upper surface of the TFT array surface, theinvention may have a structure in which a COF (Chip On Film) substratemounted with a driving LSI having a function of such as the signal linedriving circuit or the scanning line driving circuit is electrically andmechanically connected to the scanning line and the signal line of theTFT array substrate via an anisotropic conductive material.

Phase difference plates may be disposed inside a pair of polarizingplates, respectively. In this case, as a phase difference plate, acircular polarizing plate may be constructed along with the pair ofpolarizing plates by using a λ/4 plate having a phase difference ofapproximately ¼ wavelength with respect to a wavelength in a visiblelight range. In addition, a broadband circuit polarizing plate may beconstructed by combining a λ/2 plate and a λ/4 plate.

An optical compensation film may be optionally placed on either one orboth of inner surfaces of the pair of polarizing plates. By using theoptical compensation film, a phase difference of the liquid crystallayer can be compensated for when the liquid crystal device is seen froma plan view or a perspective view, so that light leakage can be reducedso as to increase contrast. In this case, the optical compensation filmmay be a negative uniaxial medium which is constructed by aligning adiscotic liquid crystal molecule or the like having a negativerefraction index anisotropy in a hybrid manner. In addition, a positiveuniaxial medium may be used which is constructed by aligning a nematicliquid crystal molecule or the like having a positive refraction indexanisotropy in a hybrid manner. Furthermore, the negative uniaxial mediumand the positive uniaxial medium may be combined for use. In addition, adouble axial medium of which refraction indices in every directionthereof meet the relation of nx>ny>nz, a negative C-plate, or the likemay be used.

Although the mobile phone is used as an electronic apparatus accordingto the above embodiments, the invention is not limited to the mobilephone. In other words, if a display unit using the liquid crystal deviceof the invention is placed, the electronic apparatus may be other typesof electronic apparatus such as an electronic book or projector, apersonal computer, a digital still camera, a television set, a viewfinder type or monitor direct-view type video tape recorder, a carnavigation system, a pager, an electronic scheduler, a calculator, aword processor, a workstation, a video telephone, a POS terminal, a PDA(Personal Digital Assistant), a touch panel, or the like.

The entire disclosure of Japanese Patent Application No. 2005-284456,filed Sep. 29, 2005 is expressly incorporated by reference herein.

1. A liquid crystal device comprising: a liquid crystal panel includinga pair of substrates which interpose a liquid crystal layer; a pluralityof light receiving elements which detect ambient light; and a controlunit which controls a display state of an image displayed on the liquidcrystal panel based on an intensity of the ambient light detected by aplurality of the light receiving elements, wherein the control unitincludes a determination unit determining that the intensity of theambient light is changed when changed amounts of the intensities of theambient light detected by equal to or more than half of the lightreceiving elements exceed a predetermined value.
 2. The liquid crystaldevice according to claim 1, wherein the determination unit determinesthat the intensity of the ambient light is changed when changed amountsof the intensities of the ambient light detected by more than half ofthe light receiving elements exceed a predetermined value.
 3. The liquidcrystal device according to claim 1, further comprising an illuminationunit which irradiates illumination light on a rear surface of the liquidcrystal panel, wherein the control unit controls an intensity of theillumination light based on the determination of the determination unit.4. A light emitting device comprising: an electro-optical panelincluding a pair of substrates which interpose an electro-opticalmaterial layer; a plurality of light receiving elements which detectambient light; and a control unit which controls a display state of animage displayed on the electro-optical panel based on an intensity ofthe ambient light detected by a plurality of the light receivingelements, wherein the control unit includes a determination unitdetermining that the intensity of the ambient light is changed whenchanged amounts of the intensities of the ambient light detected byequal to or more than half of the light receiving elements exceed apredetermined value.
 5. An electronic apparatus comprising the liquidcrystal device according to claim
 1. 6. An electronic apparatuscomprising the light emitting device according to claim
 4. 7. A methodof controlling a liquid crystal device including a liquid crystal panelincluding a pair of substrates which interpose a liquid crystal layerand a plurality of light receiving elements which detect ambient light,the method comprising: detecting an intensity of the ambient light byusing a plurality of the light receiving elements in a predeterminedtime interval; and controlling a display state of an image displayed onthe liquid crystal panel by determining that the intensity of theambient light is changed when changed amounts of the intensities of theambient light detected by equal to or more than half of the lightreceiving elements exceed a predetermined value.
 8. A method ofcontrolling a light emitting device including an electro-optical panelincluding a pair of substrates which interpose an electro-opticalmaterial layer and a plurality of light receiving elements which detectambient light, the method comprising: detecting an intensity of theambient light by using a plurality of the light receiving elements in apredetermined time interval; and controlling a display state of an imagedisplayed on the electro-optical panel by determining that the intensityof the ambient light is changed when changed amounts of the intensitiesof the ambient light detected by equal to or more than half of the lightreceiving elements exceed a predetermined value.